**18. PD-1 gene and lupus**

PD-1 (Programmed Cell Death Protein 1) discovered in 1992 and described as the rheostat of the immune reaction, because expressed in cells of the lymphoid tissue it inhibits their effector action allowing tumour development, while its blockade induces a robust anti-tumour activity and at the same time the appearance of autoimmune phenomena. Antibodies against PD-1 are currently widely used in cancer chemotherapy but are associated with induction of autoimmunity and subsequently SLE [30].
